The field to which this invention pertains is that of pipe couplings in fluid handling systems, and more particularly couplings having utility in joining an unbeaded or plain cylindrical glass pipe end portion to a beaded glass pipe end portion. The prior art is replete with pipe couplings for joining glass pipes together having both beaded and unbeaded end portions.
U.S. Pat. No. 3,084,959, to Stanton, discloses a pipe coupling having a gasket formed of either triangular or circular regions which are joined together by web sections, and held within a clamp having opposed inclined angles. Accordingly, as the clamp is being tightened about the gasket, the applied lines of force to the end regions of the gasket are directed toward the pipe ends, and tend to shorten the gasket as it is compressed about the pipe. In a like manner, U.S. Pat. No. 3,233,907 to Stanton discloses a coupling for joining pipe sections of different diameters, wherein a gasket member has a central indentation to facilitate the bending of an edge of the gasket around a bead portion of the pipe, as an outer clamp having a tapered wall is tightened about the pipe.
Tomb et al. U.S. Pat. No. 3,419,291 relates to a pipe coupling for joining unbeaded cylindrical sections of glass pipe, wherein an annular bead-like adaptor member is held around the end of an unbeaded cylindrical section of glass pipe by means of a metal band, which is bonded to the outer surface of the pipe and interlocks with the adapter member.
The Walkden U.S. Pat. No. 3,527,484 relates to a pipe coupling for joining the plain unbeaded ends of glass pipes which includes a deformable sealing gasket positioned between the abutting ends of the pipes, an elastomeric sleeve placed exteriorly around the sealing gasket, a coating of high friction material placed between the pipe and the internal surface of the elastomeric sleeve where the sleeve extends beyond the ends of the sealing gasket, and an external clamping ring having radially-inwardly extending edge portions which restrict axial expansion of the sleeve.
The Read U.S. Pat. No. 3,572,773 relates to a pipe coupling adapted for coupling the ends of two axially aligned glass pipes, embodying a tubular sealing gasket positioned over the exterior end portions of the pipes, an elastomeric sleeve placed exteriorly over the gasket to contact the gasket and the pipes, and a metallic band having tapered sidewalls positioned around the sleeve for clamping the sleeve and the gasket tightly to the end portions of the pipes while restricting axial expansion of the sleeve.
The Zine U.S. Pat. No. 3,630,550 relates to a coupling for joining a plain cylindrical and a beaded pipe end portion, which includes a resilient liner surrounded by a force-generating clamping band for each pipe end. Each clamping band has a tapered surface which axially compresses the resilient liner to prevent axial elongation thereof during the tightening of the bands.
The Nelson U.S. Pat. No. 3,633,947 relates to a coupling for joining two pipe end sections, wherein the coupling includes a resilient liner and a one-piece and having stepped interlocking and overlapping end sections. The band has tapered sidewalls cooperating with tapered sidewalls of the resilient liner for compressing the same and inhibiting axial elongation of the liner.
The Wesel U.S. Pat. No. 3,743,329 relates to a coupling for joining a plain unbeaded end and a beaded end of glass pipes, including an annular resilient liner and a clamping member. The resilient liner is provided with a load-dividing groove and pressure intensifying ridges, while the clamping member is provided with frustoconical surfaces for preventing the extrusion or expansion of the liner in an axial direction.
The present invention materially reduces the problems encountered with known couplings by providing an elastomeric sleeve having differential outer diameters and thicknesses for equalizing or predetermining the amount of compression exerted on the various pipe ends, isolation troughs for isolating segments of the elastomeric sleeve in order to create distinctive pressure zones, and a compression clamp having means formed in its outer wall for limiting the expansion of the sleeve along the axis of the pipe.